Gas compressor



J. w. NEWTON ETAI. v2,361,316

GAS COMPRESSOR Filed Aug. 18, 1942 4 Sheets-Sheet l Oct. 2 4, 1944.

Oct. 24, 1944. J, w, NEWTON ETAL GAS COMPRESSOR Filed Aug. .'18,- 1942 4sheets-sheet 2 Oct 24, 1944 J. w. NEWTON ETAL GAS COMPRESSOR Filed Aug.18, 1942 4 Sheets-Sheet 5 7M/ff Oct. 24, 1944. J. w. NEWTON ETAL2,361,316

GAS COMPRESSOR '.Filed Aug. 18, 1942 I 4 Sheets-Sheet 4 MSW PatentedOct. 24, 1944/ UNITED STATES PATENroFFicE GAS COMPRESSOR- South WalesApplication August 18, 1942, Serial No. 455,22@

' In Australia September 16, 1941 13 Claims.

'I'his invention relates to gas compressors and particularly to thosemoderate sized portable types used in industry; it has .been devised toAprovide sucha gas compressor of improved con-- struction whereby thecompressor unit and the ga's under compression can be efficientlymaintained at such low temperatures and the Ine-- chanical eillciency ofthe construction is such as will enable a single stage compressor toAachieve a compression index substantially equivalent to that of theaverage two-stage compressor when operating at similar speeds and undersimilar conditions. f

A further feature of the invention is the con'-` struction of adouble-acting compressor which by reason of the facilities afforded bythe construction to cool the working parts andthe mechanical eiiiciencythereof can be operated at speeds higher than the speeds which existingcompressors of similar dimensions can attain the clearance between theend cover and the cylinder and this gas is compressed on the next strokeof the piston. l

Unloading means are provided to restrain the movement of the cylinderand to hold it centrally between the end covers when a predeterminedcompression pressure is reached so that during K the period of restraintthe reciprocation of the discharges it again through the open ends.

Reciprocationofl the piston, is effected by a l' piston rod having thebanjo frame of a harmonic link` motion thereon. A crank pin in suchframe thereby increasing the output approximately proportionately to thespeed increase.

A still further feature oi' the invention is the combination of partswherebya compressor may` be assembled having twoopposed double-acting fcompressor cylinders having all the characteristics before mentioned.

Basically the invention is a floating self-aligning compressor cylinderwhich is free to reciprocate between end covers and is so moved by apiston reciprocating therein.

This self-aligning cylinder takes the place of the conventional intakevalve or valves and pro- I vides the utmost freedom for air intake. Theair intake is controlled by movement of the cylinder such movement beingobtained from power that would otherwise be lost in friction thaty is,the

, tension of the piston rings against the cylinder wall. This feature inaddition to providing a distinctly improved means of taking in airpermits the cooling of substantially the entire compressor heads orcovers cylinder.

On each stroke of the piston the cylinder is as weil as the compressormoved by friction of the piston to seat against the end cover in thedirection of movement of the ceeds that above the valves. 0n the returnstroke the pressure in the said ports is gradually released and thispermits of the valves seating gently. During this compression 'strokegas is the reciprocating means described. Nevertheless is the actuating'means A circulating pump actuated by the banjo frame provides a coolingliquid for the piston which liquid is passed through ducts in the banjoframe and the piston rod to. a cooling passage in the piston whichtraverses both faces thereof and the skirt.

The floating self-aligning cylinder permits the use oi.' comparativelythin metal or metal alloy which could not be used in cylinders formingan integral part, of a compressor casing as constructedfhitherto. Thisthin metal provides for the effective transfer of heat which` is takenaway by gas circulating about the outer wall thereof. The end covers arecooled by water circulation.

The cooling of the cylinder and the end covers as aforesaid coupled withthe cooling of the piston assists in the improvement of the compressionindex as previously stated and also makes possible the operationv of adouble acting com` pressor, both single and twin opposed cylinders, atVhigh speeds not heretofore obtainable.

The use of the floating self-aligning cylinder of this invention is notof necessity confined to it will be appreciated that the utilisation ofthe harmonic link motion as the means toreciproadmittedtotheothersideofthepistonthrough I6 cate the piston makesa design of utmost simcompressor; Fig. 2 is a sectional elevationV onliner-tof Fig. 1: Fig. 3 is a. section plan on line 3 3 of Fig'. 2; Fig.4 is a sectional elevation illustrating an unloading device and a modiedair cushioning means of seating the cylinder against the end covers;Figs-5 and 6 are sectional plans on lines 5-I and l-l respectively ofFig. 4; Fig. '7 is an elevation (partly in section) of a compressorhaving two double-acting opposed cylinders; Fig. 8 is a sectionalelevation approximately on line 8 8 of Fig. '1; Fig. 9 is a sectionalplan on line 9 9 of Fig. 7.

Referring to Fig. 1, the cylinder I has at each end an internal ange orlip Il which is conveniently made by screwing flanged rings I2 onto eachend of the cylinder. The face I3 of these rings l2 constitutes a seatingto seal the cylinder l0 against the end covers |4|5. On the outer wallof the cylinder I0 there is a collar 5 and there is a. spring I1 betweenthis collar I6 and a cylinder supporting ring I8 which is adjustable byscrewing on the inner (cavity) wall `|9 of cylinder casing 20, see Figs.1 and 7. Where it is desired to construct a compressor with the wall I9omitted the supporting ring I8 is mounted on the casing (see Fig. 4).This variation in the construction relates to different methods ofcooling the cylinder I0 and will be described later. The cylinder IIImay be of centrifugally spun cast iron or other metal of thin sectionwhich will provide for the effective transfer of heat through the wallto be carried away by cooling means.

It will be seen that the weight of the cylinder I0 is taken by thespring I1 and that the cylinder is free to reciprocate-between the endcovers |4|5. The amount of travelo! the cylinder I0 is very little; itcan be easily calculated to provide an unrestricted air inlet to thecylinder on the respective suction strokes.

Cylinder Il) is the compression chamber and by its movement is also anair inlet controller. The amount of projection of the internal lip II iscalculated to enable the pressure of air under compression to beutilised to assist the frictional effort of the piston in sealingthecylinder against the end covers |4-I 5 on the respective compressionstrokes. This projection also provides a surface for that small portionof the compressed air remaining in the cylinder and outlet ports oncompletion of the compression stroke to act against and so preventmovement of the cylinder I0 until the piston has moved suinciently torelease such pressure; consequently there will be no harmful back-flowof air through the inlet,

and the energy stored in the clearance volume of air is utilized inovercoming the inertia of the piston. This pressure of air also givesthe discharge or outlet valve the necessary cushioning onto its seatthus preventing valve hammer.

End covers I4| 5 are mounted on the casing 20; as the joint between theend covers is not required to resist pressure it can be a face joint.This factor enables the clearance between the piston and the end coversto be reduced to a vpractical minimum which provides for the appropriateexpansion of the metals of the respective parts thereby increasing thevolumetric efliciency of the compressor.

In the end covers |4|5 there is a seating ring 2| juxtaposed the face I3of the rings I2. This seating ring 2| may be of any resilient materialand it is secured into the end covers I4 and I5 by means of an annularscrew-threaded ring 23. Fig. 4 illustrates a metal ring piston 24 whichmay be substituted for the seating ring 2|; one such piston is slidablymounted in the annular chamber located in each of the end'covers I4 andI5. Each ring 24 is maintained in its annular chamber 25 by means of theannular screw threaded rings 26 and it is adapted to make contact withthe ilanged ring I2. by means of air pressure as will be explainedlater.

Outlet ports 21 in said end covers |4-I5 are provided with annular discvalves 28 or other outlet valves of conventional construction. Thevalves illustrated are adapted to be controlled by the springs 29located in the cup holders 30 which'are secured to the end covers |4-I5.

The covers I 4-l5 are provided withjackets 32 and 33 respectively andeach of which is furnished with a pair of compartments 34 and 35, theformer are in communication with the air outlet ports 21 and the commonoutlet 36. Through the latter a cooling medium such as water circulates,an inlet 31 and outlet 38 being provided. Additionally the cover I5 hasa stuffing box for the compressor piston rod 39. This stuiiing boxconsists of a neck ring 40, packing 4|, gland ring 42 and a gland cap 43furnished with screw threaded rods 44 to press the gland ring 42 againstthe packing 4|; the gland cap 43 is held in place by studs 45.

Casing 20 has an air inlet 41 with ports 48 to each end of the cylinderI0. Air is drawn into the compressor by the action of the piston 49therein and it may be assisted by a low pressure ian to act as asupercharger. is used it is designed to deliver more air than thecylinder can absorb the surplus passing through the ports 50 to cool thecylinder I0 and then discharging to atmosphere through port 5 I In analternative construction where a supercharger fan is not desired theinner wall I9 of the casing 20 is eliminated (see Fig. 4) thus providinga free passage of air from the air inlet 41 around the cylinder I0 andthence to the compression chamber. This construction may be preferred insome cases although there is a tendency for the intake air to becomesomewhat heated prior to entering the compression `chamber due tocontact with the cylinder I0. In this construction the cylindersupporting ring I8 is screwed onto the casing 20.

Piston 49 in the cylinder I0 is stepped as indicated at 52 to clear thelip II of the rings I2. In its piston ring fitting the piston is ofconventional construction. The tting of the piston is facilitated andthe wear on the parts in frictional Contact is minimised by the floatingand self aligning mounting of the cylinder l0. 'I'he piston 49 has acavity 53 therein and an internal boss 54 to take a piston rod 39. Thereare ports 56 communicating through the boss 54 to the cavity 53. Theseports are in register with an inlet duct 58 in the piston rod permittingthe now of cooling liquid. An outlet duct 59 in the piston rod 39permits the return of the cooling liquid after passing over the pistonsurfaces.l The cooling liquid returns to an oil sump or to an oilcooler.

On the end of the piston rod 39 is a banjo frame 60 of a harmonic linkmotion which is housed in the compressor base frame 6|. A' crank pin 62in link block 63 in said banjo frame is mounted on shaft 64 in bearings55 in the base frame 6|; said shaft 64 is rotated by an appropriatemeans.

In the single cylinder construction illustrated if; Fig- 1 the bottom$6r of the base. frame is an 011 Sump which may incorporate oil coolingmeans and in it is a pump barrel 61 having an inlet valve 68 while ahollow plunger 69 alxed to the banjo frame 60 in the same plane as thepiston rod 33 has a delivery valve 1l therein.

Where a fan The outlet from this pump is in communication with the inletduct B9 through port 1i. The outlet duct 59 in the piston rod 39terminates in the outlet 12 which is directed onta the link block 69 andcrank pin assembly. In this construction the plunger rod serves also asa. guide for the harmonic link assembly and for this purpose the upperpart of the pump barrel l1 has a substantial bearing 19. i t

Fig. r(illustrates `a compressorwith opposed cylinders while Fig. 8illustartes the piston cooling means. The compressor cylinderl andparts' 4in this construction are identical with that described withreference to Fig. l, the second lplston rod taking the place of theplunger 69. In

. is held in this position until the air pressure is` so reduced thatthe springs 93 overcome the pressure acting on the plunger 19 andwithdraw saidA 'piungers from .engagement with the said stops 11. y Thestops 11 are kept in alignment with the plungers 18 by slippers 81 onthe,cylinder I9 which are mounted between guides 98 on the cas l inglllor I9 as the case may be. Such-an unloading mechanism as described aboveor other this construction the banjo frame 90 has tw`o inlet ports 1l incommunication with the inlet ducts 59 in the respective piston rods I9and two outlet ports in communication with the 'outlet ducts 59. Thereis a piston cooling pump such as that described with reference to Fig. lfor-each compressor unit andthe plunger rods I9 are mounted incross-heads 16 on the banjo frame 9|. The outlets from these pumps arein communication with the inlet 'ports 1I.

In operation, the piston 49 moving in one di-v rection will by means ofthe piston rings tension against .the cylinder il, mov'e said cylinderuntil the ring I Z-seats on the seating ring 1l of the end coversin the4direction of movement of 'the rpiston. The piston thus causes thecylinder to make a totally enclosed area into which the piston`compresses the air-drawn in on the previous stroke of the piston-untilthe pressure is suilicient to lift the-outlet valves 29. The cylinder yI9 is kept well seated by the air pressure acting on the interna1 lip Ilof the ring I2. The pressure o n the lip Il increases proportionallywith the increase in air pressure so that such air pressure as well asthe friction of the piston controls the effective sealing of thecylinder onto the end covers. -When ring piston seatings 2l are employedas' shown in Fig. 4 each' of such seatings' 24 when the piston 49. is onthe compression stroke, is firmly pressed against the flanged rings I2by the air pressure in compartment 94 passing into the ports 90 andleading into the annular chamber 25 and impingingupon the seatings 2l.seating ring 2! on the suction side of the piston contacts theprojecting face 9| of the threaded ring 29 thus sealing the chamber 25against leakage. v

Figs. 4, 5 and 6 illustrate one form of unloading device which may beincorporated in the compressor. In this lconstruction V nosed stops 11are mounted on thecylinder I0 juxtaposed V notched plungers 18 incylinder 19 mounted in the casing 20. These cylinders 19 are dividedinto plunger compartments 89 and spring compartments 8| and a plungerrod 82 passing through the plunger compartment 80 into the springcompartment 9i. has a helical spring '93 thereon held in place' by nuts84. `Theplunger compartment has an air inlet 85 behind the plunger 19and a pipe 96 therefrom is connected to the pressure side of thecompressor through a conventional air governor. The springs' are loadedto hold the plungers'18 in the cylinders 19 until the air inthe pipe andbehind the plungers reaches a predetermined pressure when the plungersare forced outwardly against the tenvsion of the springs until the Vnotches in the lplungers 18 engage the V nosed stops 11 and vso preventmovement of the cylinder I9. In this When the piston is on the suctionstroke they suitable unloading mechanism will be incorp'orated in thecompressors as illustrated in Figs.

1 and 7; it has been omitted from the description of the mentionedfigures in order'to clarify the same.

g .Although the drawings show compressors with the cylinders on avertical axis it is to be understood that the 'compressor may beconstructed to operate with the axis of the cylinders horizontal.

We claim:

1. A gas compressor comprising a casing having a gas inlet therein, endcovers fixed to said casing, said end covers each having outlet portstherein and compartments leading from said outlet ports to a commonoutlet duct, valves on said outlet ports, means providing a water jacketin said end covers for cooling same, a cylinder in said casing springbalanced between said end covers and reciprocable between said endcovers to'cause the admission of gas to said cylinder at each endalternately, means providing a seal between the cylinder and the endcover contacted thereby, a piston rod slidably mounted in one of saidend covers and extending into said cylinder, a piston in lsaid cylinderand`connected to said piston rod, means for reciprocating said pistonrod and piston, said piston having a cavity therein and communicatinginlet and outlet ducts, means for supplying cooling liquid to saidpiston through said inlet/ duct, and means operable to unload thecompressor when a predetermined pressure has been attained.

2. A gas compressor having a cylinder reciprocable between end coversoperable to eilect the admission oi' gas to said cylinder alternately ateach end thereof, means to elect a seal between the cylinder' and theend cover-contacted by said tion in said cylinder, means forreciprocating said piston. and means for holding the cylinder stationaryfor thepurpose of unloading the compressor when a'predeterminedcompression pressure has been attained.

3. A gas compressor as claimed in claim, 2 wherein the cylinder hasastop on its outer wall,

-a notched plunger adjacent said stop, a cylinder for said plungercomprising a plunger compartment and a spring compartment, a rod on saidplunger extending into the spring compartment of the plunger cylinder, ahelical spring on said rod, a gas inlet to the plunger compartment'ofsaid plunger cylinder, means connecting said gas inlet with the pressureoutlet from the compressor, and guide means preventing rotation oi thecompressor cylinder. t I

4. A gas compressor comprising a casing having end covers, a cylinderbalanced in said casing between said end covers, a piston reciprocablein said cylinder, said cylinder being mounted in self-aligning relationin respect to the piston and arranged f or reciprocation between saidAend vcovers by the friction of the reciprocation of the when apredetermined compression' pressure hasv been attained.`

5. A gas compressor comprising a casing having end covers, a cylinderspring balanced in said casing between said end covers, a pistonreciprocable in said cylinder, said cylinder being mounted inself-aligning relation in respect to the piston and arranged forreciprocation between said end covers by the friction of thereciprocation of the piston to effect the admission of gas to saidcylinder alternately at opposite ends thereof, a flanged ring secured oneach end of the cylinder with the flange thereof projecting inwardly andforming an internal lip, means to effect a seal between the lip and theend cover contacted by said cylinder, an outlet valve in each of saidend covers, means for reciprocating said piston including means operableto maintain the same in axial alignment with said cylinder, and meansfor unloading the compressor when a predetermined compression pressurehas been attained.

6. A gas compressor comprising a casing having end covers, a cylinderfloating in said casing between said end covers, a piston reciprocablein said cylinder, said` cylinder being mounted for reciprocation betweensaid end covers by the friction of the reciprocation of the piston toeiect the admission of gas to said cylinder alternately at opposite endsthereof, an inwardly projecting lip at each' end of said cylinder, anexternal collar on said cylinder, an adjustable supporting ringinternally of the casing, a spring interposed b'etween said collar andsupporting ring, means to eiect a seal between the lip and the end.cover contacted by said cylinder, an outlet valve in each of said endcovers, means for reciprocating said piston including means operable tomaintain the same in axial alignment with said cylinder, and means forunloading the compressor when a predetermined compression pressure hasbeen attained.

'7. A gas compressor comprising a casing having end covers, a laterallyand longitudinally free floating cylinder in said casing between saidend covers, a piston reciprocable in said cylinder, said cylinder beingmounted for self-aligning concurrent and relative axial reciprocationwith and with respect to said piston between said end covers by thefriction of the reciprocation of the' piston within the cylinder toeffect the admission of gas to said cylinder alternately at oppositeends thereof, an inwardly projecting lip at each end of said cylinder, aresilient seat'in each of said end covers adjacent' the ends of saidcylinder, a valve controlled outlet port in each end cover, means forreciprocating said pistonincluding means operable to maintain the samein axial alignment with said cylinder, and means for unloading thecompressor when a predetermined compression pressurehas been attained.

8. A gas compressor comprising a casing having end covers, a laterallyand longitudinally free floating cylinder in said casing between saidend covers, a piston reciprocable in said cylinder, said cylinder beingmounted for self-aligning concurrent and relative axial reciprocationwith and with respect to said piston between said end covers by thefriction of reciprocation of the piston within the cylinder to eiect theadmission of gas to` said cylinder alternately at opposite ends thereof,an inwardly projecting lip at each end of said cylinder, a ring pistonseat slidably mounted in an annular chamber in each end cover adjacentsaid cylinder, means for admitting air under pressure to the back ofsaid piston seat, a valve controlled outlet port in each end cover,means for reciprocating said piston including means operable to maintainthe same in axial alignment with said cylinder, and means for unloadingthe compressor when a predetermined compression pressure has beenattained.

9. A gas compressor comprising a casing having a gas inlet therein, endcovers fixed to said casing, said end covers each having outlet portstherein, valves on saitl outlet ports, means providing a jacket forcooling fluid in said end covers for cooling same, a 'laterally andlongitudinally free floating cylinder in said casing spring balancedbetween said end covers and reciprocable therebetween to effect theadmission of gas to said cylinder at each end alternately, meansproviding a seal between the cylinder and the end cover contacted bysaid cylinder, a piston rod slidably mounted in one of said end coversand extending into said, cylinder, a piston in said cylinder andconnected to said piston rod, a banjo frame of a harmonic link motionconnected to' said rod, a link block in said frame, crank means in saidblock, means for rotating said crank means, and means to unload thecompressor when a predetermined compression has been attained.

10. A gas compressor as claimed in claim 9 wherein the piston has acavity therein and an internal boss in which the piston rod is secured,said boss having an inlet and an outlet port to said cavity and saidpiston rod having inlet and outlet ducts therein in register with theinlet and outlet ports of said boss, and the banjo frame of me harmoniclink motion of said piston'rod having an inlet duct in register withsaid piston rod inlet duct and with a hollow pump plunger reciprocablein a pump casing, and means for delivering liquid through said hollowpump plunger and the inlet duct and port to the cavity in said pistonupon reciprocation of said hollow pump plunger.

11. A gas compressor comprising a pair of axially aligned casings eachhaving a gas inlet therein, end covers ilxed to each of said casings,said end covers each having outlet ports therein and compartmentsleading from said outlet ports to a common outlet duct for the covers ofeach casing, valves on said outlet ports, means providing a water jacketin each oi.'A said end covers for cooling same, a laterally andlongitudinally free oating cylinder in each casing spring balancedbetween the end covers thereof and reciprocable between said end coversto effect the admission of gas to each cylinder alternately at oppositeends thereof, means providing a seal becylinder connected jto saidpiston rod, means for .reciprocating said piston rods and pistonsconjointly, and means operable to unload the compressor when apredetermined pressure has been attained.

azionario I r 5 for cooling same, a laterally and longitudinally freefloating cylinder in each casing spring balanced between'the end coversthereof and recprocable between said end covers'to eifect the admissionof gaslto'each cylinder alternately at opposite ends thereof, meansproviding a seal Vbetween each cylinder and the casing emi covercontacted thereby, apiston rod slidably mounted in each of the inner endcovers and extending into each of said cylinders, a piston in eachcylinderconnected to Said piston rod, a banjo frame of a harmonic linkmotion intermediate n said piston rods and connected thereto, a linkblock in said frame, crank means in said block, means for rotating saidcrank means, and means to Vunload the compressor when a predetermined Icompression preure has been attained. e

13. A gas compressor as claimedY in claim 12 wherein each piston has acavity' therein and an internal boss in which the piston rod is secured,said boss having therein registering outlet and llinlet ports and ductsto said cavity, crossheads on opposite sides of the banjo frame,a hollowpump plunger aiiixed to each of said cross-heads, said frame havingducts therein in register with the ducts in said piston rods and thehollow pump Il Dllmgers, pump casings for said plungers, and

means for delivering liquid through said'plungers, ducts and ports tothe piston cavities upon reciprocation of said piungers.

JOHN NEWTON.

M. J. DUFF-FYFE.

